With conventional gas insulated electric apparatuses, a high voltage conductor is accommodated in a metallic ground tank and an insulating gas is filled in the tank to afford insulation. In this case, when the gas insulated electric apparatus is assembled, metallic foreign matters enter the tank in some cases, so that an intense electric field generated in energization of the high voltage conductor causes the metallic foreign matters to float to adhere to or approach the high voltage conductor whereby the apparatus is lowered in voltage endurance in some cases.
Hereupon, with conventional gas insulated electric apparatuses, there is provided a particle trapper, in which one or more metallic rods are arranged in an axial direction of a tank, an insulating coating is applied to surfaces of the metallic rods, and particles are trapped on a low electric field portion of those portions in contact with the tank (see Patent Citation 1).
Also, with further, conventional gas insulated electric apparatuses, a particle trap, by which electrically conductive particles are trapped, is provided on a lower portion of a tank, and a guide plate is bent in a sawtooth configuration and arranged with downward inclination thereof toward the particle trap whereby particles are trapped (see Patent Citation 2).
Further, with further, conventional gas insulated electric apparatuses, a metallic plate, on which a plurality of smooth wavy irregularities are continuously arranged in an alternate manner, is provided on an inner surface of a vessel and an insulating coating is applied to concave portions to trap foreign matters on low electric field portions of the concave portions (see Patent Citation 3).    Patent Citation 1: JP-UM-A-56-145313 (page 3, line 14 to page 4, line 4, FIGS. 5 and 6)    Patent Citation 2: JP-UM-A-56-73124 (page 4, line 16 to page 5, line 12, FIGS. 3 to 5)    Patent Citation 3: JP-UM-A-62-57511 (page 3, lines 11 to 14, page 4, lines 4 to 8, FIG. 1).